Pressure safety release industrial air exhaust silencer

ABSTRACT

An air exhaust silencer comprises a barrel which has a piston head, the barrel is contained for reciprocation within a cylinder and is normally retained in the cylinder in an inwardly retracted position so as to permit air exhaust through the silencer structure supported within the barrel and which embodies a pair of gas permeable frequency distorters adapted to muffle the noise of the exhaust air to below a predetermined maximum noise level; the barrel containing cylinder of the silencer is provided with a plurality of relief ports which are in open communication with a normally closed off relief chamber in front of the piston head; regulated fluid pressure retaining means are employed to normally retain the barrel in the retracted position; upon build-up of back pressure in the silencer assembly, due to clogging of the gas permeable members of the silencer, the increased air pressure through the silencer becomes sufficient to move the barrel of the silencer out of the cylinder overcoming the magnitude of the fluid pressure retaining means to establish communication between the relief chamber and the inlet port of the silencer to thereby permit air pressure to bypass said clogged gas permeable members of the silencer for direct passage to the atmosphere.

United States Patent Blatt PRESSURE SAFETY RELEASE INDUSTRIAL AIR EXHAUST SILENCER Leland F. Blatt, 790 Shoreham Road, Grosse Pointe, Mich. 48236 March 17, 1971 Inventor:

Filed:

Appl. No.:

U.S.Cl ..I8l/37, 181/45, l8l/65 Int. Cl. ..FOIn 1/10, FOln 1/20, FOln 3/00 Field olSeareh ..l8l/36-38, 36 A,

References Cited UNITED STATES PATENTS FOREIGN PATENTS OR APPLICATIONS 1,372,464 8/1964 France ..l8l/65 Primary Examiner-Robert S, Ward, Jr. Art0rneyDaniel G. Cullen et al.

[is] 3,675,733 [451 July 11,1972

[ ABSTRACT An air exhaust silencer comprises a barrel which has a piston head, the barrel is contained for reciprocation within a cylinder and is normally retained in the cylinder in an inwardly retracted position so as to permit air exhaust through the silencer structure supported within the barrel and which embodies a pair of gas permeable frequency distorters adapted to muflle the noise of the exhaust air to below a predetermined maximum noise level; the barrel containing cylinder of the silencer is provided with a plurality of relief ports which are in open communication with a normally closed off relief chamber in front of the piston head; regulated fluid pressure retaining means are employed to normally retain the barrel in the retracted position; upon build-up of back pressure in the silencer assembly, due to clogging of the gas permeable members of the silencer, the increased air pressure through the silencer becomes sufficient to move the barrel of the silencer out of the cylinder overcoming the magnitude of the fluid pressure retaining means to establish communication between the relief chamber and the inlet port of the silencer to thereby permit air pressure to bypass said clogged gas permeable members of the silencer for direct passage to the atmosphere.

7 Clalrrs, 3 Drawing PA'TENTEDJUL 1 1 1972 FIG. I

FIG.2

fa 4a INVENTOR LELAND F. BLATT ATTORNEYS PRESSURE SAFETY RELEASE INDUSTRIAL AIR EXHAUST SILENCER REFERENCE TO RELATED APPLICATIONS The present application relates in part to the air exhaust silencer structure disclosed in applicants co-pending application, Ser. No. 91,125, filed Nov. 19, 1970, now US. Pat. No. 3,612,214, issued Oct. 12, 1971, for Pressure Release Safety Industrial Air Exhaust Silencer" and comprises a further improvement thereof.

BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates to mufilers or silencer structures and more in particular to an air exhaust silencer of the type disclosed in applicants afore mentioned co-Pending application, Ser. No. 91,125.

As described in detail in the above referred to copending application, these types of silencers are incorporated in industrial applications for air valve outlets or venturis on air operated tools, pneumatic presses and the like.

The silencer of the present invention, and as described in the afore mentioned co-pending application, has a barrel type housing providing an inlet for attachment to a respective air exhaust. The housing contains one or more frequency distorters made of porous material, such as sintered bronze, ceramic or the like, and in certain applications may also include a frequency modulator of foam material disposed between two adjacent frequency distorters.

It is evident that with the type of porous material used for the frequency distorting and frequency modulating members of the silencer, if the air exhaust lines to which the silencer is attached carry any foreign material, such as debris, scale, hard grease, etc. the foreign material conveyed by the stream of air will be carried into the silencer and eventually clog the porous frequency distortion members, which act as a filter letting only air through at a certain flow rate, the foreign material carried by the air flow being caused to adhere to the surface of the porous frequency distortion members. Clogging of the porous members through which the exhaust air is caused to pass, of course, considerably decreases the flow efficiency through the silencer and creates a back pressure.

In most ordinary applications, this will present no great problem other than the possible slow-down of the operating equipment to which the silencer is attached. However, in some particular applications, such as in clutch or brake valve applications for a pneumatic press, clogging of the porous members in the silencer will eventually cause the valve to malfunction and, thus, the brake or clutch of the press cannot be operated properly, with the result that the press ram would automatically continue to reciprocate without the usual intermittent stop and start requirement of the ram. This, of course, creates a considerable safety hazard and may also result in costly damage to the machinery.

In view of the foregoing, the present invention provides an improved, pressure release, safety mechanism for this type of silencer which is effective to maintain a constant flow rate from the exhaust through the silencer or directly to the atmosphere. Thus, in the event that the porous members of the silencers should become severely clogged, the increased air flow pressure through the silencer is effective to actuate the safety release mechanism, causing the air flow to be directly diverted to the atmosphere by bypassing the clogged porous frequency distortion members of the silencer, until such time at which the clogged porous members will have been cleaned or replaced.

in the afore mentioned co-pending application the barrel of the silencer assembly, which carries the frequency distortion member, is maintained in retracted position within an outer cylinder surrounding the barrel by mechanical means such as shear pins or expansion springs which would give way when subjected to a certain pressure magnitude.

Although these arrangements in the prior application are sufficiently effective for most applications to exhausts of valve operated brake or clutch release mechanisms of a particular machinery, it has been found that in certain instances an increased versatility of pressure release adjustment will be required to accommodate varying operating fluid pressures. In other words, in the prior arrangements of applicant's co-pending application the shear pin strength or, respectively, the compression force of the biasing spring can only be designed at a fixed pressure magnitude to be operable.

Accordingly, applicants present application provides for a variable adjustment of the normal operating retaining force to normally close off the pressure relief ports to the atmosphere. This is accomplished by the provision of a regulated fluid pressure system acting on the barrel of the silencer in such way as to normally retain the barrel of the silencer in the retracted position within the cylinder housing and which pressure can be regulated by means of a manual pressure regulator incorporated in the fluid system. Thus, the retaining pressure acting on the barrel of the silencer can be adjusted to accommodate various operating conditions of the machinery or respectively accommodate varying operating fluid pressures of, for instance, valve mechanisms for operation of brake or clutch release means of a machinery such as found in heavy presses and the like. The fluid pressure magnitudes for these valve mechanisms are usually designed to be operable between a minimum and a maximum pressure magnitude within which the brake or clutch release mechanisms are effectively operable.

Accordingly, the present improved silencer pressure relief mechanism incoporates adjustable features to accommodate a wide range of operating pressures for fluid pressure operated mechanisms as above described without the need of any physical or structural alterations in the silencer structure itself.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings illustrate a preferred embodiment of the invention in which:

FIG. 1 is a longitudinal cross-section through the improved embodiment utilizing regulated fluid pressure to normally maintain the silencer in operating condition;

FIG. 2 illustrates the arrangement of FIG. 1 in the extended position for bleeding off air pressure directly to the atmosphere; and

FIG. 3 is a front end view of the device including a diagram of the regulated fluid pressure system.

DETAILED DESCRIPTION OF THE INVENTION With reference to the drawings, the improved embodiment of the combined silencer and pressure relief assembly, generally indicated at 10, is composed of a cylindrical housing 12 closed by an outer end cap 14 having a pilot section 16 extending into said housing 12 and which provides the seat for a seal ring 18. The other end of the cylindrical housing 12 is closed by a port cap 20 similarly provided with a pilot portion 22 which extends into the housing 12 providing a seat for a similar seal ring 24. The two end caps 20 and 14 are tied together by a plurality of tie rods 46, as is customary in cylinder designs of this kind.

The cylinder 12 is attached to the air exhaust pipe 34 of the particular device or tool to which the silencer structure is applied, by means of a threaded bore 36 in end cap 20, which provides the inlet into the silencer structure.

The cylindrical housing 12 is adapted to receive a silencer assembly 38 composed of a cylindrical barrel 40 which outer end is supported in sliding engagement with the internal surface of the outer end cap 14. The inner radial surface of the outer end cap 14 is provided with a seal assembly 42 for sealing engagement around the barrel 40.

The inner end of the barrel member 40 carries a piston head 44 adapted for reciprocation within the cylinder 12.

It will be noted that the outer diameter of the barrel member 40 is of substantially smaller dimension than the inner diameter of the cylinder 12 to thereby provide a radial chamber 46 between the barrel 40 and cylinder 12.

The outer end of the barrel 40 of the silencer assembly 38 retains a pair of frequency distorter members 52 and 54, respectively, of identical construction and assembled in backto-back relationship. The frequency distorter members 52 and 54 are of axially extending dome shaped configuration such that the member 52 extends through the barrel 40 forwardly towards the inlet 36 and the other member 54 extends axially outwardly of both the barrel 40 and cylinder 12. Each of the frequency distorter member 52 and 54 is provided with an opposed radial flange 56 and 58, respectively, which are disposed in abutting relationship and retain a sealing member 60 in between them. In order to retain the members 52 and 54 in position, the flange 56 of the member 52 abuts against an inner shoulder 62 within the barrel 40 and the other flange 58 of the other member 54 is clamped against flange 56 by means ofa lock ring 64'.

As more fully in detail described, in co-pending application Ser. No. 81,051, filed Oct. 15, 1970, shaped frequency distorter members 52 and 54 are made of a porous material such, as for instance, sintered bronze, ceramic or the like, having a predetermined density which varies with the particular application of the silencer assembly. Altemately, the density of the porous material of the frequency distorter member 52 may be different from that of the other frequency distorter member 54 to thereby obtain sequential noise reduction of the exhaust air passing through the silencer assembly 38.

In certain applications, and particularly in applications where different noises at different frequencies must be absorbed by the silencer and additional noise reduction baffle member of porous nature may be provided and which would be located between the dome shaped frequency distorter members 52 and 54 as disclosed in the above mentioned copending application. This baffle member, which appropriately can be called a frequency modulator, is made of a foamed urethane or any similar porous material.

In accordance with the present invention, the front end 41 of the barrel member 40 of the silencer 38 is seated on an axially inwardly extended hub portion 21 of the end cap which is provided with a seal assembly 64 for sealing engagement against the barrel member 40. The piston 44, which may be integrally formed as a radial flange on the barrel member 40, is located a predetermined distance rearwardly of the front end 41 of the barrel member 40. Thus, in the normal operating position of the silencer assembly 38, as shown in FIG. 1, a second radial chamber 66 is formed between the end cap 20 and the piston 44 of the barrel member 40. The second radial chamber 66 under normal operating conditions shown in FIG. 1, is normally closed off from the inlet 36 of the silencer assembly by means of sealing engagement of the front end 41 of the barrel member 40 on the axial hub portion 21 of the end cap 20. The cylindrical housing 12 is provided with a plurality of relief ports 68 circumferentially arranged around the housing. The relief ports 68 are in constant communication with the second radial chamber 66 for connection of the chamber 66 with the atmosphere. Thus, the second radial chamber 66, in front of the barrel piston 44, defines an air exhaust relief chamber normally closed off against the interior of the silencer 38.

As further contemplated in the present improved safety exhaust device, the radial chamber 46 between the rear end of the barrel piston 44 and end cap 14 is connected by means of an inlet 70 provided in the end cap 14 to a source of fluid under pressure, indicated at 72 in FIG. 3. The fluid pressure maintained in the radial chamber 46 to normally maintain the barrel assembly 40 of the silencer 38 in retracted position within the cylindrical housing 12, is adapted to be manually regulated by a regulator 74 installed between the source 72 and the fluid inlet 70. Additionally, as is common practice, a one-way check valve is provided between the source 72 and the regulator 74, said check valve being shown at 76.

Thus, in accordance with the present invention, the fluid pressure within the radial chamber 46 of the assembly 10 acting against the barrel piston 44 is adapted to be accurately adjustable by means of the manual regulator 74 relative to the exhaust pipe 34 of the device to which the assembly 10 is attached, which may vary under certain operating conditions.

The pressure within the radial chamber 46 of assembly 10 acting on the cross sectional piston area of 44, may be adjusted to maintain the silencer assembly 38 in a retracted position within the cylindrical housing 12 with 41 in contact with seal 64 so to permit the air to exhaust through the hemispherical silencing elements 52 and 54.

If the pressure in 46 were to be increased proportionally a greater percentage of clogging could be tolerated, still permitting the air to exhaust through the silencing elements. Should these hemispherical frequency distorting members become clogged to such an extent that an increase in back pressure at the inertial exhaust instant would be great enough to upset the difi'erential maintained in radial chamber 46, silencing assembly 38 would move outward within housing 12, removing end 41 of barrel 40 from its sealing position on the axial housing portion 21, and allowing the excess pressure to exhaust through chamber 66 and relief ports 68.

When the inlet pressure at 36, at the cracking inertial exhaust instant, would be bled off to atmosphere lowering the back pressure acting on hemispherical element 52 to less than the pressure on piston 44 within chamber 46, the exhaust silencer assembly 38 would reseat itself on seal 64 in rest position for another exhaust cycle and will continue to relieve any back pressure and reseat itself until the porous members of the hemispherical exhaust chambers are cleaned by removing the cogging debris.

The direct bleed-off exhaust air from the exhaust pipe 34 to the atmosphere through ports 68, causes a considerable increase in noise level of the assembly 10 to thereby signal to the operator of the machine, or other device to which the silencer is attached, that the noise level reduction members of the silencer need to be cleaned from contaminants or, respectively, need to be replaced.

It will be apparent that the present improved safety pressure release mechanism is able to be positively controlled at adjustable pressure differentials in accordance with required minimum safe operating pressures of the air operated device or machinery, (such as for instance a clutch or brake mechanism of a press), to which the silencer is attached.

Furthermore, by location of the release ports 68 as close as possible to the inlet port 36, a more effective, fast acting and immediately responsive pressure release is accomplished to positively prevent any damage to the air operated mechanism to which the present improved device is attached.

Similarly, back pressure created by clogged conditions of the porous noise reducing members 52-54, is substantially reduced to a safe minimum at such level as not to affect the safe operation of the clutch or brake mechanism or similar mechanism to which the silencer device 10 is attached.

Although the present invention has been shown and, described in connection with a silencer structure incorporating a pair of dome shaped noise reducing or frequency distortion members, the safety pressure relief mechanism of the present invention is similarly applicable to silencer structures of the kind as for instance disclosed in applicant's co-pending prior application Ser. No. 8 1,05 l supra.

It will be obvious to a person skilled in the art to which the present invention pertains that various changes in arrangement and detail may be asserted to without departing from the spirit and essential characteristic of the invention as defined in the appended claims.

I claim:

1. In combination with an air exhaust silencer assembly comprising a barrel having at least one gas permeable member disposed therein made of a porous material to permit the passage of air therethrough, the improvement comprising: a pressure release mechanism including a cylinder having an open end; a closure plate including an air inlet port at the other end of said cylinder for attachment to an air exhaust; said barrel of said silencer extending through said open end into said cylinder and being provided with a piston head adjacent its inner end for sliding engagement within said cylinder; said cylinder being provided with at least one relief port in open communication with a pressure release chamber formed between said piston head and said closure plate normally closed off towards said inlet port; fluid pressure means to normally retain said barrel within said cylinder under normal operating conditions of said silencer; said fluid pressure means being of a magnitude to yield at a predetermined magnitude of pressure build-up within said silencer assembly to permit said barrel to be moved outwardly to said cylinder by increased pressure on said piston to thereby expose said release chamber for communication with said inlet port to bleed off excess air pressure directly to the atmosphere; and means to regulate fluid pressure in predetermined relationship with normal operating exhaust pressure through said silencer.

2. In the silencer assembly as defined in claim 1, said cylinder having an end cap for reciprocable extension of said barrel therethrough; said barrel being of smaller diameter than the internal diameter of said cylinder to form a radial chamber between said barrel and said cylinder and between said piston head onsaid barrel and said end cap of said cylinder; said radial pressure chamber being connected to a source of fluid under pressure and said regulating means defining a manually operable fluid pressure regulator between said radial pressure chamber and said source of fluid under pressure to thereby maintain said barrel in a retracted position within said cylinder at adjustable pressures to normally close off said pressure release chamber to said inlet port during normal exhaust operating conditions through said silencer assembly.

3. In the silencer assembly as defined in claim 2, said air inlet closure plate being provided with an axially inwardly extending seat portion being adapted to receive the front end of said barrel within said cylinder; and said piston head on said barrel being located a distance inwardly from said front end to thereby form a second radial chamber between said piston head and said front closure plate defining said pressure release chamber.

4. In the silencer assembly as defined in claim 3, said cylinder being provided with a plurality of radially spaced relief ports in open communication with said pressure release chamber.

5. In the silencer assembly as defined in claim 3, said axially inwardly extending portion of said air inlet closure plate being provided with a radial seal assembly sealingly engaging the internal surface of the front end of said barrel to prevent air leakage from said inlet into said release chamber under normal operating conditions of said silencer assembly.

6. In combination with a fluid pressure operated valve mechanism for a clutch or brake device of a machine operable at a predetermined fluid pressure; said fluid pressure operable valve mechanism having an air exhaust, a silencer assembly at-. tached to said air exhaust to mufile the noise created by the exhausting air; said silencer assembly comprising a cylinder, noise level reduction means within said cylinder defining a barrel head and a piston head supported for reciprocating movement within said cylinder in coaxial relationship therewith; said noise reduction means including a first pressure chamber; a second pressure chamber between said barrel and the interior of said cylinder at the rear of said piston head; means to regulate the pressure in the second pressure chamber to maintain said barrel in retracted position within said cylinder under normal air exhaust conditions through said noise reduction means; said barrel being adapted to be moved outwardly of said cylinder at a predetermined fluid pressure differential between said first and said second chamber; said cylinder being provided with a fluid pressure relief means forwardly of said piston head of said barrel effective upon movement of said barrel outwardly of said cylinder to bleed off excess air pressure from said exhaust directly to the atmosphere.

7. A pressure relief mechanism for an exhaust silencer adapted to be connected to an exhaust port of an air operated device in which the said silencer comprises: a cylindrical barrel having at least one gas permeable member disposed therein for passage of air therethrough from said exhaust at predetermined pressure magnitude and flow rate; the gas permeable member being adapted to reduce the exhaust noise of air flow through the silencer; said safety pressure relief mechanism comprising: a cylindrical housing adapted to surround said barrel; said cylindrical housing at one end having a cap member defining an air inlet co-axially aligned with said exhaust of said device; the other being provided with an end wall having an aperture for reciprocable extension and sliding support of said barrel therethrough; the inner end of said barrel being provided with a piston head; said cylinder being provided with at least one relief port normally not in communication with said inlet; fluid pressure means to normally releasably retain said barrel in retracted position within said cylinder; said fluid pressure retaining means being operable at a preselected magnitude of excess pressure within said barrel to be overcome to permit said barrel to be moved out of said cylinder due to the increased fluid pressure within said barrel; and said fluid pressure retaining means being manually adjustable to accommodate a variety of operable fluid pressure magnitudes.

end of said cylindrical housing 

1. In combination with an air exhaust silencer assembly comprising a barrel having at least one gas permeable member disposed therein made of a porous material to permit the passage of air therethrough, the improvement comprising: a pressure release mechanism including a cylinder having an open end; a closure plate including an air inlet port at the other end of said cylinder for attachment to an air exhaust; said barrel of said silencer extending through said open end into said cylinder and being provided with a piston head adjacent its inner end for sliding engagement within said cylinder; said cylinder being provided with at least one relief port in open communication with a pressure release chamber formed between said piston head and said closure plate normally closed off towards said inlet port; fluid pressure means to normally retain said barrel within said cylinder under normal operating conditions of said silencer; said fluid pressure means being of a magnitude to yield at a predetermined magnitude of pressure build-up within said silencer assembly to permit said barrel to be moved outwardly of said cylinder by increased pressure on said piston to thereby expose said release chamber for communication with said inlet port to bleed off excess air pressure directly to the atmosphere; and means to regulate fluid pressure in predetermined relationship with normal operating exhaust pressure through said silencer.
 2. In the silencer assembly as defined in claim 1, said cylinder having an end cap for reciprocable extension of said barrel therethrough; said barrel being of smaller diameter than the internal diameter of said cylinder to form a radial chamber between said barrel and said cylinder and between said piston head on said barrel and said end cap of said cylinder; said radial pressure chamber being connected to a source of fluid under pressure and said regulating means defining a manually operable fluid pressure regulator between said radial pressure chamber and said source of fluid under pressure to thereby maintain said barrel in a retracted position within said cylinder at adjustable pressuRes to normally close off said pressure release chamber to said inlet port during normal exhaust operating conditions through said silencer assembly.
 3. In the silencer assembly as defined in claim 2, said air inlet closure plate being provided with an axially inwardly extending seat portion being adapted to receive the front end of said barrel within said cylinder; and said piston head on said barrel being located a distance inwardly from said front end to thereby form a second radial chamber between said piston head and said front closure plate defining said pressure release chamber.
 4. In the silencer assembly as defined in claim 3, said cylinder being provided with a plurality of radially spaced relief ports in open communication with said pressure release chamber.
 5. In the silencer assembly as defined in claim 3, said axially inwardly extending portion of said air inlet closure plate being provided with a radial seal assembly sealingly engaging the internal surface of the front end of said barrel to prevent air leakage from said inlet into said release chamber under normal operating conditions of said silencer assembly.
 6. In combination with a fluid pressure operated valve mechanism for a clutch or brake device of a machine operable at a predetermined fluid pressure; said fluid pressure operable valve mechanism having an air exhaust, a silencer assembly attached to said air exhaust to muffle the noise created by the exhausting air; said silencer assembly comprising a cylinder, noise level reduction means within said cylinder defining a barrel head and a piston head supported for reciprocating movement within said cylinder in coaxial relationship therewith; said noise reduction means including a first pressure chamber; a second pressure chamber between said barrel and the interior of said cylinder at the rear of said piston head; means to regulate the pressure in the second pressure chamber to maintain said barrel in retracted position within said cylinder under normal air exhaust conditions through said noise reduction means; said barrel being adapted to be moved outwardly of said cylinder at a predetermined fluid pressure differential between said first and said second chamber; said cylinder being provided with a fluid pressure relief means forwardly of said piston head of said barrel effective upon movement of said barrel outwardly of said cylinder to bleed off excess air pressure from said exhaust directly to the atmosphere.
 7. A pressure relief mechanism for an exhaust silencer adapted to be connected to an exhaust port of an air operated device in which the said silencer comprises: a cylindrical barrel having at least one gas permeable member disposed therein for passage of air therethrough from said exhaust at predetermined pressure magnitude and flow rate; the gas permeable member being adapted to reduce the exhaust noise of air flow through the silencer; said safety pressure relief mechanism comprising: a cylindrical housing adapted to surround said barrel; said cylindrical housing at one end having a cap member defining an air inlet co-axially aligned with said exhaust of said device; the other end of said cylindrical housing being provided with an end wall having an aperture for reciprocable extension and sliding support of said barrel therethrough; the inner end of said barrel being provided with a piston head; said cylinder being provided with at least one relief port normally not in communication with said inlet; fluid pressure means to normally releasably retain said barrel in retracted position within said cylinder; said fluid pressure retaining means being operable at a preselected magnitude of excess pressure within said barrel to be overcome to permit said barrel to be moved out of said cylinder due to the increased fluid pressure within said barrel; and said fluid pressure retaining means being manually adjustable to accommodate a variety of operable fluid pressure magnitudes. 